Lower alkyl esters of 1-cinnamyl-3-methyl-4-phenylpiperidine-4-carboxylic acid



United States Patent 3,012,030 LOWER ALKYL ESTERS 0F 1-CINNAMYL-3- METI-IYL-4=PHENYLPlPERIDINE-4-CARBOX- YLIC ACID Paul A. J. Janssen, Antwerpse Steenweg 16, Vosselaar,

near Turnllout, Belgium N0 Drawing. Filed Apr. 29, 1960, Ser. No. 25,528 4 Claims. (Cl. 260-240) The present invention relates to compounds expressed by the general formula COzR In this formula R can represent methyl, ethyl, straight or branched-chm'n propyl, butyl, amyl, and hexyl radicals. The cistrans isomerism which arises at positions 3 and 4 results in the production of isomers in preparations involving these centers. For the sake of simplicity the lower melting isomer has been designated a and the higher melting ,8. In the individual compound names this symbol has been included in the designation of the 3-methyl group. Experience in the art suggests that the ff isomer is probably that in which the 3-methyl group is as to the ester grouping at position 4 while the 5 isomer is of the opposite or trans configuration.

The compounds of this application can be prepared by a route which begins with tosylation of-2-hydroxyethyl-2- hydroxypropylamine; the tosylation product is converted to the corresponding dihalide, which is then condensed with phenylacetonitrile to give a 1-tosyl-3-methyl-4- cyano-4-phenylpiperidine. The nitrile is hydrolyzed, and the resultant acid is esterified. Removal of the tosyl mo1ety and subsequent alkylation gives the compounds of the invention.

These compounds are analgesic agents; the evidence suggests that the more potent species possess the ,8 configuration. They also possess barbiturate potentiating and hyponouc activity, and are of special interest because of their low mydriatic activity.

The following examples are presented to further illustrate the invention; they should not be construed as limitmg it in spirit or scope. Quantities of solids are given in parts by weight, and temperatures are in degrees centigrade C.).

Example 1 A mixture of 119 parts of 2-hydroxyethyl-2-hydroxypropylamine and 54 parts of sodium carbonate in 450 parts of water is heated to 70 C.; 190.5 parts of p-toluenesulfonyl chloride are added, and the resultant mixture is heated at 95 C. for one hour. At the end of this time the reaction mixture is cooled to 0 C. and filtered. The filter cake is extracted with ether, the ether is removed from the extracts, and the residue is taken up in isopropyl alcohol. Petroleum ether is added to the alcohol solution, and the resulting solution is chilled to 20 C. Two crops of crystals are collected, and can be used without further purification in the remainder of the procedure to follow. Purification can be effected by recrystallization from ethanol-acetone; the sample of N-(2-hydroxyethyl)- N-(Z-hydroxypropyl)-p-toluenesulfonamide prepared in this Way melts at'66.2-68.2 C.

A mixture of 450 parts of the dihydroxy amide in 690 parts of thionyl chloride is heated at 125 C. for one hour, and then cooled. The excess thionyl chloride is evaporated and the residue is taken up in 360 parts of dry toluene; the toluene solution is filtered and reduced in 3,012,030 Patented Dec. 5, 1961 2 volume to yield N-(Z-chloroethyl)-N-(2-chloropropyl)-ptoluenesulfonamide.

A solution of 400 parts of the dichloro amide and 152 parts of sodamide in toluene is heated to about 45 C.; parts of phenylacetonitrile is added, in portions, and the resultant mixture is heated'under reflux for 2 hours, then for 56 hours at room temperature. At the end of this time water is added, and the organic layer is removed and reduced in volume. The residue is treated with hot methanol; filtration of the resultant mixture and concentration of the filtrate gives 1-(4-methylbenzenesulfonyl)- 3a-methyl-4-phenyl-4-cyanopiperidine; the purified sample melts at 143.5446 C. The methanol-insoluble portion is recrystallized from butanol to give l-(4-methylbenzenesulfonyl)-3B-methyl-4-phenyl-4-cyanopiperidine, melting at 217218 C.

A mixture of 71.5 parts of the [3 isomer, 71.5 parts of potassium hydroxide, and 700 parts of ethylene glycol is heated at 170 C. for 9 hours and then poured into water. The resultant suspension is filtered and the filtrate is acidified with hydrochloric acid to precipitate l-(4- methylbenzenesulfonyl) 3,9 methyl 4 phenylpiperidineA-carboxylic acid. The purified sample melts at 209.5-211.4 C. Similar treatment of the u isomer provides l-(4-methylbenzenesulfonyl)-3ot-rnethyl-4-phenylpiperidine-4-carboxylic acid, melting at l73.4l75.8 C.

Example 2 A suspension of 20 parts of 1-(4-methylbenzenesulfonyl)-3,8-methyl-4-phenylpiperidine-4-earboxylic acid in 225 parts of thionyl chloride is stirred until a clear solution is obtained. The excess thionyl chloride is removed, and the residue is dissolved in parts of methanol. The methanol solution is stirred and heated under refiux overnight and then cooled to 0 C., to give methyl l-(4-methylbenzenesulfonyl) 3,3 methyl 4 phenylpiperidine 4- carboxylate, melting at l37.4-140.3 C. Analogous treatment of the a isomer provides methyl 1-(4-methylbenzenesulfonyl) 3oz methyl 4 phenylpiperidine 4 carboxylate melting at 94.595.4 C.

Example 3 By the method of the preceding example, the acid chloride from 1-(4-methylbenzenesulfonyl)-3fl-methyl-4- phenylpip-eridine-4-carboxy1ic acid is treated with ethanol to give ethyl 1-(4-methylbenzenesulfonyl)-3fl methyl4- phenylpiperidinel-carboxylate, melting at 102l04.6 C. The a isomer, prepared similarly, melts at 127.8- 128.2 C.

Example 4 A sample of 1-(4-methylbenzenesulfonyl)-3p-methyl-4- phenylpiperidine-4-carboxylic acid is converted to the acid chloride as described in Example 2 and this halide is condensed with isopropyl alcohol to yield isopropyl 1-(4- methylbenzenesulfonyl)S S-methyl 4 phenylpiperidine- 4-carboxylate, melting at l12.5113.2 C. The a isomer is prepared similarly, and melts at 99-1015 C.

Example 5 A mixture of 78 parts of methyl 1-(4-methylbenzenesulfonyl)-3fl-methyl-4-phenylpiperidine-4-carboxylate, 59 parts of phenol and 500 parts of a saturated solution of hydrogen bromide in acetic acid is stirred at room temperature for about 20 hours. Ether is added, and the resultant solution is extracted with water. The water layer is made alkaline with sodium hydroxide, and the basic solution is extracted with ether. The ether solution is dried over magnesium sulfate and then concentrated. Distillation of the residue gives methyl 3,3-methy1- 4-phenylpiperidinel-carboxylate which boils at 131- 133/0.4 mm. This compound forms a hydrochloride,

which melts at l9l192.2 C. Methyl 3a-methyl-4 phenylpiperidinel-carboxylate, prepared similarly, boils at l22l23/0.02 mm.

Example 6 Application of the method of the preceding example to ethyl 1-(4-methylbenzenesul'fonyl) 3t? methyl-4-phenylpiperidine-4-carboxylate yields ethyl 35-methyl-4-phenyh piperidinel-carboxylate, boiling at l26/().2 mm. compound forms a hydrochloride, which melts at 175.6- 176.2 C. Ethyl 3a-methyl-4-phenylpiperidine-4-carboxylate, similarly prepared, forms an oxalate Which melts at l36.2137.4 C.

Example 7 A sample of isopropyl l-(4-methylbenzenesulfonyl)-3B methyl-4-phenylpiperidine-4-carboxylate, treated by the procedure of Example 5, gives isopropyl 35-methyl-4- phenylpiperidinel-carboxylate, boiling at 124126/0.02 mm. Isopropyl 3a-methyl-4-phenylpiperidine-4-carboxylate, boiling at 136/ 0.6 mm. is prepared similarly.

Example 8 Example 9 The method of Example 8, on application to ethyl 3,8-

4 methyl-4-phenylpiperidiue-4-carboxylate, yields the hydrochloride of ethyl l-cinnamyl-3/3-methy1-4-pheuylpiperidine-4-carboxylate, melting at 205.5206 C.

Example 10 Isopropyl 3 ,B-methyl-4-phenylpiperidine 4-carboxy1ate undergoes allcylation and subsequent salt formation by the procedure of Example 8 to give the hydrochloride of isopropyl l-cinnamyl-3 8-methyl-4-phenylpiperidine-4-carboxylate, melting at l77.6178.2 C.

What is claimed is:

1. A compound of the structural formula QCH=OHOHrN 2. Methyl 1-cinnamyl-3,8-methyl-4-pheny1piperidine-4- carboxylate.

3. Ethyl carboxylate.

4. Isopropyl l-cinnamyl-3lit-methyl-4-phenylpiperidine- I C O O(lower allzyl) 1-cinnamy1-3 B-rnethyl-4 phenylpiperidinet- 4-carboxylate.

References Cited in the file of this patent UNITED STATES PATENTS 2,813,874 Bruce et al. Nov. 19, 1957 2,824,875 Elpern Feb. 25, 1958 2,858,316 Merren Oct. 28, 1958 2,880,211 Elpern Mar. 31, 1959 2,901,487 Elpern Aug. 25, 1959 FOREIGN PATENTS 629,196 Great Britain Sept. 14, 1949 

1. A COMPOUND OF THE STRUCTURAL FORMULA 